Welded Interior Box-Column to I-Beam Connections

This paper deals with experimental investigations to study the ultimate load behavior of I-beam to box-column connections stiffened externally. Specimens representative of interior columns in a steel building frame were fabricated with connections stiffened by T-sections butt-welded at the junction of the beam and column flange. They were tested to failure under static and fluctuating loads applied separately. Ultimate load-carrying capacity and typical load-deflection and moment-rotation responses obtained experimentally are presented; the results for those specimens tested under static loading are compared with the corresponding results using the elasto-plastic finite-element method. Close agreement is observed between the experimental and theoretical moment-rotation curves. Results show clearly that these connections satisfy the basic criteria: sufficient strength, sufficient rotation capacity, and adequate stiffness for a moment connection. The proposed connections are capable of developing load-carrying capacity in excess of the plastic capacity of the beams framing into the joint.